NEW YORK (Reuters Health) - Rape victims treated with psychotherapy are still more than twice as likely to have sexual difficulties and pelvic pain than unvictimized women, according to a new study.

But it's unclear from this study whether the pelvic and sexual difficulties are a direct result of physical rape trauma or are a physical manifestation of post-traumatic stress disorder (PTSD), a severe anxiety disorder that up to half of rape victims will experience.

The "findings are consistent with a growing body of research," said Steven Bruce, director of the Center for Trauma Recovery at the University of Missouri-St. Louis, who was not involved in the study.

Researchers already knew that victims of chronic sexual abuse in childhood were at risk for sexual problems, according to coauthor Iva Biancic of the National Psychotrauma Center for Children and Youth at University Medical Center in Utrecht, the Netherlands.

"We found evidence that victims of single rape during adolescence have an equal risk to develop such problems," she told Reuters Health.

The researchers asked 18 women in their late teens and early twenties who had been raped during adolescence and treated for PTSD about their sexual functioning, and compared the answers to those of 114 college-aged women who had never been victimized.

About 30 percent of the rape victims had pelvic floor hypertonicity, or "too-tight vagina," compared to 12 percent of the nonvictimized group, according to results published in the Journal of Sexual Medicine.

Both groups had the same level of sexual activity.

The study had a number of weaknesses, according to Mary Koss of the University of Arizona in Tucson, who has served on the National Academy of Sciences Panel on Violence Against Women.

The rape victims had a lower average education level than the comparison group, which indicates that the groups may not have been similar in many other ways, Koss said.

She also noted that "pelvic floor problems" could be a direct physical consequence of rape, especially since most of the women were underage and could have been as young as 12 or 13 when the rape happened, but those details aren't included in the results.

Many rape victims are asymptomatic and never seek psychotherapy, so she warns that women in that category may be disturbed by these results.

"The bad news is there are people out there who might not have thought of this and end up feeling dejected," Koss said.

"Clearly, all PTSD interventions are not alike and there is considerable variability in the amount of success following any intervention," said Tara Galovski, who studies PTSD for victims of assault at the University of Missouri-St. Louis.

Galovski agreed that the study would need to include more details about the state of each woman's mental health at the time of the study and the physical trauma suffered during the rape for the results to be useful for practitioners, she told Reuters Health.